1. Field of the Invention
The present invention relates to an imprint apparatus for transferring a mold pattern as an original onto a substrate such as a wafer, and an article manufacturing method using the imprint apparatus.
2. Description of the Related Art
The imprint technique is already known as a technique replacing a method of forming fine patterns on semiconductor devices by using ultraviolet, X-ray, or electron-beam photolithography. In the imprint technique, a mold having a fine pattern is pressed (imprinted) against a substrate such as a wafer coated with a resin material (a wafer on which the resin material is dispensed) by, for example, electron-beam exposure, thereby transferring the pattern onto the resin. Imprinting has several types of methods. As one method, the photo-curing method is proposed in, for example, Japanese Patent Laid-Open No. 2005-533393. In the photo-curing method, while a transparent mold is pressed against a resin with which a substrate is coated, the resin is cured by irradiation with ultraviolet light, and the mold is detached (released) from the cured resin. The imprint technique using this photo-curing method is suitable for the manufacture of semiconductor integrated circuits because temperature control is relatively easy to perform and an alignment mark on the substrate can be observed through the transparent mold. Also, when overlaying different patterns, it is possible to apply the step-and-repeat method by which a mold matching the chip size of a device to be manufactured is formed and the patterns are sequentially transferred onto shots on a substrate.
In the imprint technique, mold release by which the mold is detached from the cured resin is generally regarded as a problem. If the mold is forcedly detached from the resin while the releasability is low, the mold may be damaged, and this sometimes decreases the durability of the imprint apparatus. Japanese Patent Laid-Open No. 2008-246729 discloses a method of detecting the release force, determining the presence/absence of abnormality by comparing the detected release force with a threshold value, and, if abnormality is found, improving the releasability by, for example, heating a mold.